Any explanation about the ubuntu version please? What's the difference between 14.1 and 15.1? I think I may have to use SID in debian.

Don't really know... I had some problems with 14.1 at the time and upgrading the distro seemed like an easy fix. Very happy with it and its been stable. Otherswise I do know that 15.04 uses more watts, boots slightly slower, and uses more cpu power to run than 14.1- according to one review I read.